Elemental composition of Tibetan Plateau top soils and its effect on evaluating atmospheric pollution transport.

The Tibetan Plateau (TP) is an ideal place for monitoring the atmospheric environment of low to mid latitudes. In total 54 soil samples from the western TP were analyzed for major and trace elements. Results indicate that concentrations of some typical "pollution" elements (such as As) are naturally high here, which may cause incorrect evaluation for the source region of these elements, especially when upper continental crust values are used to calculate enrichment factors. Because only particles <20 microm are transportable as long distances, elemental concentrations of this fraction of the TP soils are more reliable for the future aerosol related studies over the TP. In addition, REE compositions of the TP soils are unusual, highly characteristic and can be used as an effective index for identifying dust aerosol from the TP.